LXR linux/arch/arm/mach-footbridge/isa-rtc.c

   1/*
   2 *  arch/arm/mach-footbridge/isa-rtc.c
   3 *
   4 *  Copyright (C) 1998 Russell King.
   5 *  Copyright (C) 1998 Phil Blundell
   6 *
   7 * CATS has a real-time clock, though the evaluation board doesn't.
   8 *
   9 * Changelog:
  10 *  21-Mar-1998 RMK     Created
  11 *  27-Aug-1998 PJB     CATS support
  12 *  28-Dec-1998 APH     Made leds optional
  13 *  20-Jan-1999 RMK     Started merge of EBSA285, CATS and NetWinder
  14 *  16-Mar-1999 RMK     More support for EBSA285-like machines with RTCs in
  15 */
  16
  17#define RTC_PORT(x)             (0x70+(x))
  18#define RTC_ALWAYS_BCD          0
  19
  20#include <linux/init.h>
  21#include <linux/mc146818rtc.h>
  22#include <linux/bcd.h>
  23#include <linux/io.h>
  24
  25#include "common.h"
  26
  27void __init isa_rtc_init(void)
  28{
  29        int reg_d, reg_b;
  30
  31        /*
  32         * Probe for the RTC.
  33         */
  34        reg_d = CMOS_READ(RTC_REG_D);
  35
  36        /*
  37         * make sure the divider is set
  38         */
  39        CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
  40
  41        /*
  42         * Set control reg B
  43         *   (24 hour mode, update enabled)
  44         */
  45        reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
  46        reg_b |= 2;
  47        CMOS_WRITE(reg_b, RTC_REG_B);
  48
  49        if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
  50            CMOS_READ(RTC_REG_B) == reg_b) {
  51                /*
  52                 * We have a RTC.  Check the battery
  53                 */
  54                if ((reg_d & 0x80) == 0)
  55                        printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
  56        }
  57}
  58